1. Field of the Invention
This invention pertains to testing of power levels on video signal lines. More particularly, this invention pertains to a non-invasive system for such testing.
2. Description of the Prior Art
In certain industries, such as the video transmission industry, signals are directed from a source along a coaxial cable. For example, in the cable TV industry, video signals may be collected at a facility by satellite receivers. The signals will be transmitted across coax cables at a base band level. From time to time, it is desirable to monitor the signals in order to set power levels. In fact, industry and government regulations require that certain power levels be maintained in cable TV signals.
In order to test the power level of cable TV signals coming from a source, the signal must be routed to test equipment. Such equipment requires that the signal coming into the test equipment is at the same power level as the signal coming from the source equipment. A reduction in the power of the signal coming into the test equipment will result in unreliable testing of the signal by the test equipment.
Prior art switching coax jacks with monitors (such as U.S. Pat. No. 4,749,968 to Burroughs) were not adequate for permitting access to the signal for testing purposes. For example, with a prior art switching coax jack, a signal could not be drawn off a monitor port and then tested at the test equipment since the signal at the monitor port is reduced in power relative to the signal coming into the jack. As a result, reliable testing off the monitor port was not possible.
With switching coax jacks of the prior art, a plug could be inserted into the OUT port of the jack to divert the entire signal to the test equipment. However, such a system would require interrupting service to a customer.
In present CATV installations, when it is desired to test the power level of a signal, the entire signal is commonly diverted to the test equipment. This results in interrupting the service to a customer. Accordingly, testing of power in CATV installations is typically done during off-peak hours (such as 2 a.m.). This requires having testing technicians available on site outside of normal business hours for the purpose of testing signals. In addition to being disruptive to the scheduling of technicians, such requirements may also be expensive since they may require payment of premium wages to technicians to work during such off-peak hours.